#region Copyright & License

//
// Copyright 2001-2005 The Apache Software Foundation
//
// Licensed under the Apache License, Version 2.0 (the "License");
// you may not use this file except in compliance with the License.
// You may obtain a copy of the License at
//
// http://www.apache.org/licenses/LICENSE-2.0
//
// Unless required by applicable law or agreed to in writing, software
// distributed under the License is distributed on an "AS IS" BASIS,
// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
// See the License for the specific language governing permissions and
// limitations under the License.
//

#endregion

using System;
using log4net.Core;

namespace log4net.Filter {
  /// <summary>
  /// This is a very simple filter based on <see cref="Level"/> matching.
  /// </summary>
  /// <remarks>
  /// <para>
  /// The filter admits two options <see cref="LevelToMatch"/> and
  /// <see cref="AcceptOnMatch"/>. If there is an exact match between the value
  /// of the <see cref="LevelToMatch"/> option and the <see cref="Level"/> of the 
  /// <see cref="LoggingEvent"/>, then the <see cref="Decide"/> method returns <see cref="FilterDecision.Accept"/> in 
  /// case the <see cref="AcceptOnMatch"/> option value is set
  /// to <c>true</c>, if it is <c>false</c> then 
  /// <see cref="FilterDecision.Deny"/> is returned. If the <see cref="Level"/> does not match then
  /// the result will be <see cref="FilterDecision.Neutral"/>.
  /// </para>
  /// </remarks>
  /// <author>Nicko Cadell</author>
  /// <author>Gert Driesen</author>
  public class LevelMatchFilter : FilterSkeleton {
    #region Member Variables

    /// <summary>
    /// flag to indicate if the filter should <see cref="FilterDecision.Accept"/> on a match
    /// </summary>
    bool m_acceptOnMatch = true;

    /// <summary>
    /// the <see cref="Level"/> to match against
    /// </summary>
    Level m_levelToMatch;

    #endregion

    #region Constructors

    #endregion

    /// <summary>
    /// <see cref="FilterDecision.Accept"/> when matching <see cref="LevelToMatch"/>
    /// </summary>
    /// <remarks>
    /// <para>
    /// The <see cref="AcceptOnMatch"/> property is a flag that determines
    /// the behavior when a matching <see cref="Level"/> is found. If the
    /// flag is set to true then the filter will <see cref="FilterDecision.Accept"/> the 
    /// logging event, otherwise it will <see cref="FilterDecision.Deny"/> the event.
    /// </para>
    /// <para>
    /// The default is <c>true</c> i.e. to <see cref="FilterDecision.Accept"/> the event.
    /// </para>
    /// </remarks>
    public bool AcceptOnMatch {
      get { return m_acceptOnMatch; }
      set { m_acceptOnMatch = value; }
    }

    /// <summary>
    /// The <see cref="Level"/> that the filter will match
    /// </summary>
    /// <remarks>
    /// <para>
    /// The level that this filter will attempt to match against the 
    /// <see cref="LoggingEvent"/> level. If a match is found then
    /// the result depends on the value of <see cref="AcceptOnMatch"/>.
    /// </para>
    /// </remarks>
    public Level LevelToMatch {
      get { return m_levelToMatch; }
      set { m_levelToMatch = value; }
    }

    #region Override implementation of FilterSkeleton

    /// <summary>
    /// Tests if the <see cref="Level"/> of the logging event matches that of the filter
    /// </summary>
    /// <param name="loggingEvent">the event to filter</param>
    /// <returns>see remarks</returns>
    /// <remarks>
    /// <para>
    /// If the <see cref="Level"/> of the event matches the level of the
    /// filter then the result of the function depends on the
    /// value of <see cref="AcceptOnMatch"/>. If it is true then
    /// the function will return <see cref="FilterDecision.Accept"/>, it it is false then it
    /// will return <see cref="FilterDecision.Deny"/>. If the <see cref="Level"/> does not match then
    /// the result will be <see cref="FilterDecision.Neutral"/>.
    /// </para>
    /// </remarks>
    public override FilterDecision Decide(LoggingEvent loggingEvent) {
      if (loggingEvent == null)
        throw new ArgumentNullException("loggingEvent");

      if (m_levelToMatch != null && m_levelToMatch == loggingEvent.Level) // Found match
        return m_acceptOnMatch ? FilterDecision.Accept : FilterDecision.Deny;
      return FilterDecision.Neutral;
    }

    #endregion
  }
}